Technical Field
This disclosure relates to measurement instruments, and more particularly to inductive position encoders that may be utilized in precision measurement instruments.
Description of the Related Art
Various encoder configurations may include various types of optical, capacitive, magnetic, inductive, movement and/or position transducers. These transducers use various geometric configurations of a transmitter and a receiver in a read head to measure movement between the read head and a scale. Magnetic and inductive transducers are relatively robust to contamination, but not perfectly so.
U.S. Pat. No. 6,011,389 (the '389 patent) describes an induced current position transducer usable in high accuracy applications, U.S. Pat. Nos. 5,973,494 (the '494 patent) and 6,002,250 (the '250 patent) describe incremental position inductive calipers and linear scales, including signal generating and processing circuits, and U.S. Pat. Nos. 5,886,519 (the '519 patent), 5,841,274 (the '274 patent), and 5,894,678 (the '678 patent) describe absolute position inductive calipers and electronic tape measures using an induced current transducer. U.S. Pat. No. 7,906,958 (the '958 patent) describes an induced current position transducer usable in high accuracy applications, wherein a scale having two parallel halves and a plurality of sets of transmitting coils and receiving coils mitigates certain signal offset components that may otherwise produce errors in an induced current position transducer. All of the foregoing are hereby incorporated herein by reference in their entireties. As described in these patents, an induced current transducer may be manufactured using printed circuit board technology and is largely immune to contamination.
However, such systems may be limited in their ability to provide certain combinations of features desired by users, such as combinations of signal strength, compact size, high resolution, cost, robustness to misalignment and contamination, etc. Configurations of encoders that provide improved combinations would be desirable.